const {Readable}=require("stream");

class MyReadable extends Readable{
    constructor(){
        super();
        this.currentChar=97;
    }
    __read(){
        if(this.currentChar<=122){
            this.push(String.fromCharCode(this.currentChar));
            this.currentChar++;
        }else{
            this.push(null);
        }
    }
}
const myReadable=new MyReadable();
myReadable.pipe(process.stdout);
